Embolus Blood Clot Filter and Delivery System

ABSTRACT

A blood filter delivery system for delivering a filter into a vein includes an introducer and a push rod with a spline member disposed along the push rod. The spline member has a main body, and first and second boss portions spaced apart along the longitudinal axis to provide a gap for retaining anchor member of the filter during delivery via the introducer.

PRIORITY DATA AND INCORPORATION BY REFERENCE

This application is a continuation of U.S. application Ser. No.13/706,079, now U.S. Pat. No. 9,387,063, which is a continuation of U.S.application Ser. No. 13/300,469, now U.S. Pat. No. 8,430,903, which is acontinuation of U.S. application Ser. No. 11/997,832, now U.S. Pat. No.8,062,327, which is a U.S. national stage application under 35 U.S.C.371 of International Application No. PCT/US2006/017890, filed May 9,2006, which claims priority to U.S. Provisional Patent Application No.60/706,596, filed Aug. 9, 2005, the entireties of which are herebyincorporated by reference.

FIELD OF THE INVENTION

This invention relates to a filter device that can be placed via acatheter delivery system in a vessel of a mammalian body to reduce therisk of embolisms. If needed, such filter can be removed from the vesselof a mammalian body without causing traumatic damage to the vessel of amammalian body.

BACKGROUND OF THE INVENTION

In recent years, a number of medical devices have been designed whichare adapted for compression into a small size to facilitate introductioninto a vascular passageway and which are subsequently expandable intocontact with the walls of the passageway. These devices, among others,include blood clot filters which expand and are held in position byengagement with the inner wall of a vein, such as the vena cava. Thesevena cava filters are generally designed to remain in place permanently.Such filters include structure to anchor the filter in place within thevena cava, such as elongate diverging anchor members with hooked endsthat penetrate the vessel wall and positively prevent migration ineither direction longitudinally of the vessel. The hooks on filters ofthis type are rigid, and within two to six weeks after a filter of thistype has been implanted, the endothelium layer grows over the diverginganchor members and positively locks the hooks in place. Now any attemptto remove the filter results in a risk of injury to or rupture of thevena cava.

A number of medical procedures subject the patient to a short term riskof pulmonary embolism which can be alleviated by a filter implant. Insuch cases, patients are often averse to receiving a permanent implant,for the risk of pulmonary embolism may disappear after a period ofseveral weeks or months. However, most existing filters are not easilyor safely removable after they have remained in place for more than twoweeks, and consequently longer-term temporary filters that do not resultin the likelihood of injury to the vessel wall upon removal are notavailable.

One potential problem with the known delivery device is that the filter(including the elongated pusher on which the filter is attached thereon)can be pulled backward (i.e., proximally) towards the user, which mayresult in the inadvertent separation of the pusher assembly and thefilter within the delivery device.

Another potential problem that can arise during delivery of a filterresults from the placement of various hooks in a delivery device whichcan lead to the hooks entangling or interfering with one another.

SUMMARY OF THE INVENTION

The various embodiments provide for a blood filter delivery system thatresolves potential problems of the known delivery system and filter. Thesystem includes at least in part a catheter introducer, a storagemember, an elongated assembly, and a blood filter. The catheterintroducer has a coupling port connected to an elongated generallytubular member. The storage member can be coupled to the coupling portof the introducer and an adaptor, a Y-adaptor such as a Touhy-BorstAdapter. The elongated assembly provides a pusher assembly that has afirst end that can be disposed in the storage member and a second endextending out of the Touhy-Borst Adapter. The elongated assembly caninclude a handle, a pusher, a spline member, and the blood filter. Thehandle can be disposed along a longitudinal axis of the elongatedassembly proximate the second end. The pusher is disposed along thelongitudinal axis proximate the first end of the elongated assembly. Thespline member can be disposed on the elongated assembly along thelongitudinal axis between the handle and the pusher. The spline membercan have first and second boss portions spaced apart along thelongitudinal axis to provide a circumferential gap or spacetherebetween. Alternatively, the spline member can have a single bossportion with splines and grooves. In an assembled, pre-deliveryconfiguration, a blood filter, which has a plurality of anchor membersdisposed about the longitudinal axis each having a hook on their ends,is positioned between. the pusher and the gap. Each anchor member ispositioned within a spline on the first boss portion of the splinemember, with an anchor portion disposed in the groove of the splinemember.

In yet another aspect, the various embodiments also include a pusherassembly that can be utilized with a vena cava filter delivery unit. Thepusher assembly includes an elongated member, a handle, a pusher and aspline member. The elongated member extends along a longitudinal axisfrom a first end to a second end. The elongated member has a pluralityof different cross-sections at various locations along the elongatedmember. The handle is disposed proximate the first end. The pusher isdisposed proximate the second end. The member is disposed along thelongitudinal axis between the handle and the pusher. The member has amain body, and first and second boss portions spaced apart along thelongitudinal axis to provide a circumferential gap disposed about thelongitudinal axis configured so that the gap accommodates a hook of ablood filter. Preferably, the member can be a spline member.Alternatively, the spline member can have a single boss portion withsplines and grooves.

In yet a further aspect of the various embodiments, a method ofdelivering a blood filter is provided. The blood filter has a pluralityof anchors about a longitudinal axis. Each of the anchors has a hook andat least two of the anchors define a span intersecting the longitudinalaxis. The method can be achieved by locating a curved portion of eachhook in an circumferential gap of a support assembly, the gap beingdisposed between two boss portions of the support assembly; locating aportion of each anchor in a longitudinal groove or spline that extendsthrough one of the two boss portions; and enclosing the filter,including the plurality of locators and hooks, and the boss portions ina generally tubular member having an outside diameter of less than about10 French (about 3.3 millimeters). Alternatively, the spline member canhave a single boss portion with splines and the method can be achievedby positioning an anchor member within a spline in the boss and locatingthe curved portion of each hook proximal to the boss.

In yet a further aspect of the various embodiments, a bio-active agentcan be coupled to the blood filter delivery system or push rod assemblydescribed here. Alternatively, a bio-active agent may be delivered bythe blood filter delivery system.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitutepart of this specification, illustrate presently preferred embodimentsof the invention, and, together with the general description given aboveand the detailed description given below, serve to explain features ofthe invention.

FIGS. 1, 2A, 3A, 4, 5A, and 6A illustrate the components of oneembodiment of a blood filter delivery system.

FIGS. 2B and 2C illustrate a proximal portion of a catheter introducerillustrated in FIG. 2A.

FIGS. 3B, 3C, and 3D illustrate various portions of a catheter dilatorillustrated in FIG. 3A.

FIG. 4 is a cross sectional perspective view of Touhy-Borst Adapter.

FIGS. 5A and 5B illustrate a filter storage tube.

FIG. 6A illustrates an embodiment of an elongated push wire assembly.

FIGS. 6B and 6C illustrate a splined member of FIG. 6A in two operatingconfigurations.

FIGS. 6D, 6E and 6F illustrate embodiments for coupling the splinemember illustrated in FIGS. 6B and 6C to the push wire assemblyillustrated in FIG. 6A.

FIGS. 7A and 7B illustrate, respectively, a side view of a filter in astorage tube and coupled to the splined member of FIG. 6B and asectioned view of the same.

FIG. 8 illustrates the deployment of various locators of a filter as thefilter would be deployed in a vessel of a mammalian body.

FIGS. 9A, 9B, 9C and 9D illustrate components of respective bloodfilters usable with the delivery system of FIGS. 1, 2A, 3A, 4, 5A, and6A.

FIG. 10 illustrates an alternative embodiment of the spline member.

FIG. 11 illustrates a filter anchor member positioned about the splinemember illustrated in FIG. 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The various embodiments will be described in detail with reference tothe accompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.

As used herein, the terms “about” or “approximately” for any numericalvalues or ranges indicates a suitable dimensional tolerance that allowsthe part or collection of components to function for its intendedpurpose as described herein. Also, as used herein, the terms “patient”,“host” and “subject” refer to any human or animal subject and are notintended to be limit the systems or methods to human use, although useof the subject invention in a human patient represents a preferredembodiment.

The blood filter delivery system in the various embodiments mechanicallyintegrates components to safely and reliably deliver and emplace a bloodfilter, like that illustrated in FIG. 9A, within a patient's bloodvessel, such as the inferior vena cava. The system connects with afilter prepackaged in a filter storage tube 15 and includes the toolsfor properly positioning the filter in the vein and then initiating itsdeployment in a reliable fashion. Portions of the system may beprepackaged with the filter in the filter storage tube 15.

FIGS. 1-11 illustrate one of many exemplary embodiments. In an overview,as shown in FIG. 1, the blood filter delivery system 100 includes astorage tube 15 containing the filter 14, a catheter-like introducer 16and a pusher assembly 12 to push the filter 14 from the storage tube 15,through the introducer 16 and then into the blood vessel, as well assupporting adapters. The blood filter delivery system 100 for a bloodfilter device is provided that extends along a longitudinal axis A-A.Components of the system include an adapter, such as a Y-adapter, and inparticular a Touhy-Borst Adapter 10 (FIGS. 1 and 4), a filter storagetube 15 (FIGS. 1 and 5A) coupled to the Touhy-Borst Adapter 10 with afilter 14 stored in the storage tube 15 with an elongated pusherassembly 12 (FIG. 6A) that can be used to deploy the filter 14 (FIGS. 9Aand 9B) in a blood vessel of a mammal. Other components that can be usedwith the system include a catheter introducer 16 (FIG. 2A) and acatheter dilator 18 (FIG. 3A). Each of the components in the system 100is described in further details below.

Referring to FIGS. 2A, 2B, and 2C, the catheter introducer 16 includesan elongated generally tubular member, referred to herein as anintroducer sheath 16A coupled to a coupling port 16B via an introducerbody 16C, which can be provided with a fluid valve 16D. The elongatedintroducer sheath member 16A is coupled to the introducer body 16C bysuitable coupling techniques, such as, but not limited to, for example,threading, bonding, welding, swaging or adhesives. The introducer body16C can be provided with an internal taper portion 16F that allows forinsertion of the external taper portion 15C of the storage tube 15 andto allow for insertion of the filter tip 14E1 or 14E2 withoutinterference by misalignment of the storage tube 15 to the introducersheath 16A during insertion of the storage tube 15 into the introducer16. Each of the respective taper portions 16F and 15C is provided with ataper angle of about 10 degrees to about 45 degrees with respect to thelongitudinal axis A-A. The introducer sheath member 16A can be formedfrom a suitable polymer or a combination of polymers and othermaterials.

In various embodiments, the introducer sheath member 16A can be formedfrom a range of biocompatible flexible materials, such as polyurethane,polyethylene, polyamide, polyether block amide (PEBA), nylon, andcombinations thereof, preferably from a combination of PEBA 70D with aPEBA 55D proximate the tip 16A1. The introducer sheath member 16A can beconnected to the introducer body 16C by a bio-compatible adhesive, e.g.,cyanoacrylates. In an embodiment, the distal tip 16A1 of the introducersheath member 16A can be provided with a suitable radio-opaque marker,or include radio-opaque marker substances within the material of theintroducer tip 16A1. As used herein, a radio-opaque marker is anymaterial that is identifiable to machine or human readable radiographicequipment while the material is inside a subject's body, such as, by wayof example but not by way of limitation, gold, tungsten, platinum,barium sulfate, or tantalum. Preferably, a tantalum radio-opaque markeris formed on or near the tip 16A1 of the introducer sheath 16A.

In a preferred embodiment, the introducer sheath 16A has an outsidediameter of less than about 10 French and an inside diameter of lessthan about 9 French and more preferably, an outside diameter of about 9French or less and an inside diameter of about 7 French or less,depending upon limits imposed by the diameter of the blood filter in thepre-deployed (i.e., folded) configuration. The introducer sheath 16A canhave a length between approximately 305 mm and approximately 920 mm, andmost preferably approximately 735 mm.

The introducer body 16C can be provided with a coupling port 16B, whichcan include a fluid seal 16E interposed between the port opening 16B1coupled to the introducer sheath member 16A. The fluid seal 16E can beany suitable seal, such as but not limited to, a membrane or a flexiblearcuate sectioned seal disposed about a central opening. Preferably, theseal 16E is an elastic membrane made of a suitable biocompatibleelastomer, e.g., silicone, with the arcuate sectioned seal disposedabout a generally central opening 16B1 for insertion of the dilator 18or the filter storage tube 15. The introducer body 16C can be coupled toa fluid valve 16D via a polymeric (e.g., PVC) tubing 16F to allow for asuitable fluid (e.g., saline or a bio-active agent including drugs) tobe introduced into the introducer sheath 16A or to drain fluid from theintroducer member 16A. Preferably, the introducer valve 16D andintroducer body 16C are made of polycarbonate, polyethylene,polyurethane, polyarnide or PEBA. The coupling port 16B is be providedwith an edge 16B2 that can be configured to act in a snap-lockarrangement with a complementary boss portion 18H of the dilator body18A to attach and retain the dilator body 18A to the introducer body16C. That is, the coupling port 16B includes the port body 16C that hasthe port opening 16B1, which has a seal 16E occluding the opening 16B1,and the port body 16C has the edge 16B2 (which may be circumferentially)disposed about the opening 16B1 so as to allow the introducer body 16Cto be securable to a projection 15A formed on one end of the storagetube 15 via a sudden sharp engagement. The projection 15A of the storagetube 15 includes a curved surface disposed circumferentially about thelongitudinal axis A-A.

During an implantation procedure, a clinician (e.g., surgeon or clinicalradiologist) forms an opening to a vessel via a suitable puncturedevice. Thereafter, a catheter dilator 18 is used in conjunction withthe introducer 16 to provide a conduit to the internal of the body sothat contrast agent or dye can be provided into the body to determinethe implantation site. Referring to FIGS. 3A-3D, the dilator 18 includesa dilator hub 18A coupled to a dilator tube 18B. The dilator body 18A isprovided with a threaded fitting 18F at the proximal end to connect to asuitable fluid valve, e.g., the Touhy-Borst Adapter 10 so that fluidscan be injected into the dilator fluid passage 18G. A number of fluidscan be injected during operation, including dye marker for enablingfluoroscopic imaging of the introducer 16 within the patient, saline toflush body fluids from and provide lubrication within the introducer 16and, in some embodiments, cooled saline to maintain temperatures of thepush wire and/or the filter below their martensitic-to-austenitictransition temperature. The dilator body 18A is coupled to a dilatortube 18B that extends longitudinally to provide a longitudinal passage18G of approximately 661 millimeters from the dilator body 18A to thedistal dilator end 18C. At the distal dilator end 18C, the dilator tube18B can be provided with a generally truncated conic tip defined by theouter surface of the distal end 18C. The conic tip is utilized to allowthe dilator to be inserted through valve 16E and the introducer sheath16A. The conic tip 18C1 can be defined by a conic outer surface thatextends at a conic angle 0 of about 4 degrees with respect to thelongitudinal axis with an inside diameter ID of about 1 millimeter(about 0.041 inches) and an outside diameter OD of about 2.1 millimeters(about 0.084 inches).

A plurality of fluid communicating ports 18D may be provided through thewall of the dilator tube 18B in a generally spiral configuration toallow for injection of contrasting dye. Each fluid communicating port18D can be of a suitable configuration such as, but not limited to, forexample, circular, square, diamond. Preferably, six circularcommunicating ports 18D1, 18D2, 18D3, 18D4, 18D5, and 18D6 are providedwith an opening diameter of about 0.037 inches, and each port is spacedapart from the adjacent port over a distance d of about 0.16 inchesalong the longitudinal axis A-A and angularly disposed about thelongitudinal axis A-A over an interval of 60 degrees with respect toeach adjacent port.

One or more radio-opaque marker band 18E may be coupled to the dilatorbody 18A by a suitable technique, such as, but not limited to, forming aradio-opaque material integrally with the dilator tube 18B or mounting aseparate radio-opaque material onto or inside the dilator tube 18B.Preferably, two radio-opaque markers 18E are swaged onto the dilatortube 18B near the distal end 18C, with a first marker 18E1 located atapproximately 28 millimeters from the tip 18C and a second marker 18E2located at approximately 28 millimeters from the first marker 18E1. Inthese locations relative to the tip 18C, the radio-opaque markers 18E1and 18E2 enable a clinician to approximate the inside diameter of ablood vessel under fluoroscopic imaging. In the exemplary embodiments,the ports 18D1-D6 are arranged in a spiral configuration between tworadio-opaque marker bands.

Also preferably, the dilator tube 18B can be formed from a variety ofbiocompatible flexible materials, such as polyurethane, polyethylene,polyamide, polyether block amide (PEBA), nylon, and combinationsthereof, preferably from a HDPE/LLDPE blend of polymer and 18-20% ofbarium sulfate by weight, with the barium sulfate providing theradio-opaque functionality.

When assembled, the dilator tube 18B slides inside the introducer sheath16A such that the dilator tube tip 18C1 extends through the introducertip 16A1. The introducer 16 and catheter dilator 18 can be packagedseparately, such as in separate sterilized packages, so they can beunsealed and assembled by the clinician at the time of the procedure.Alternatively, the catheter dilator 18 can be inserted into theintroducer 16 at the manufacturer and sealed together in a sterilepackage, such that the clinician can unpack and use the two componentsas a unit.

Referring to FIG. 4, the Touhy-Borst Adapter 10 may be provided with atleast two passages. A first passage 10A allows for movements of thepusher rod. A second passage 10B allows for flow of saline into theintroducer 16 to increase, in most cases, lubricity between theelongated pusher assembly 12 and the introducer 16 as the elongatedpusher assembly 12 is moved along longitudinal axis A-A through thesecond passage 10B and the passage of the introducer 16. The salinesolution also can be chilled before introduction into the Touhy-BorstAdapter 10.

Referring to FIGS. 5A and 5B, a storage tube 15 for various bloodfilters (e.g., FIGS. 9A and 9B) can be introduced between theTouhy-Borst Adapter 10 and the introducer 16 in the delivery system 100.The storage tube 15 is provided with a suitable fitting (e.g., threaded,snap or luer fitting) at both ends. In the preferred embodiments, thestorage tube 15 has a threaded fitting 15B at one end to connect withthe Touhy-Borst Adapter 10 and a snap fitting 15A at the other end toconnect with the introducer 16, as well as a taper section 15C forinsertion into the preferably triple arcuate sectioned elastomeric seal16E. Alternatively, one end can be provided with a snap-fitting and theother end can be provided with a threaded fitting. The storage tube 15can be formed from any of a number suitable polymers and, preferably,polycarbonate.

Referring to FIG. 6A, an embodiment of the elongated pusher assembly 12is shown separate from other components of the delivery system 100. Inparticular, the pusher assembly 12 can be provided with a handle 12Acoupled to an elongated member 12B with various cross-sectional areas12B1, 12B2, 12B3, 12B4, 12B5, 12B6 and so on at various locations alongthe pusher assembly 12 from proximate the handle 12A to a pusher 12C.For example, near the handle 12A, the assembly 12 can be provided with ahollow stainless steel tube 12B1 connected to a suitable alloy material,including, for example, a shape memory alloy (e.g., Nitinol), wire onwhich various members can be disposed thereon such as a stop member orboss portion 12D, spline member 12E and the pusher member 12C. Thepusher assembly 12 has a longitudinal length in the range of about 800mm to about 1000 mm, preferably of about 907 mm. The handle 12A can beformed of a number of metallic, polymer or plastic materials, and ispreferably formed from PEBA coupled to a stainless steel hollow section12B1 having a diameter of about 0.041 inches. The handle 12A is coupledto a super-elastic shape-memory alloy wire having various diameters(e.g., shown at 12B2-12B6) smaller than the diameter of the stainlesssteel section 12B1 with a diameter at the distal end of about 0.013inches connected to a generally cylindrical pusher 12C. The utilizationof decreasing cross-sectional areas in the pusher assembly allows forflexibility at the distal end and pushability at the proximal end.

The terminal distal end of the generally cylindrical pusher member 12Cis longitudinally spaced from a nearest portion of the spline member 12Eat a distance of about 34 mm. The pusher member 12C is configured topush against the filter's hub 14D (illustrated in FIG. 8) as the pusherassembly 12 is advanced into the introducer 16. The spline member 12E isconfigured with a number of radially positioned splines that alternatewith grooves in a first portion 12E, each spline being sized toaccommodate one of the elongated portions of the anchor members 14B1,14B2, 14B3, 14B4, 14B5, and 14B6, providing lateral positioning of theanchor member while the filter 14 is in the stored configuration. Thepusher member 12C is separated from the spline member 12E by a flexiblenarrow cross section portion of the pusher wire 12B6 which provides avolume for accommodating both the anchor members 14 b and thepositioning members 14C of the filter 14. The distal end of the pushermember 12C is separated from the distal end of the spline member 12E bya distance LP2, which is separated from the boss 12E2 by distance LP1.Thus, the overall distance from the distal end of the pusher member 12Cto the boss 12E2 of the spline member 12E is distance LP. In otherwords, LP=LP1+LP2 where LP1 is measured from the planar surface PS tothe terminal end 12G and LP2 is measured from the terminal end 12G ofthe spline member 12E to distal end of the pusher member 12C. Tofacilitate deployment of the filter 14, the length LP and preferably LP3is slightly longer than the length LF (FIG. 7A) of the filter 14 in thepre-stored or pre-deployed configuration inside the storage tube 15.This dimensional parameter is believed to impart a lateral force orpreload unto the hub of the filter 14. As a consequence, the anchormembers are stretched and the push wire portion 12B6 is compressed inthe stored configuration. When the filter 14 is deployed and theintroducer sheath 16A is retracted proximally sufficient to uncover thehook ends of the anchor members 14A, the anchor members move radiallythereby releasing the preload force. Hence, the preload in pusher wireportion 12B6 provides a spring force that helps ensure that theanchoring members are released out of constrainment by the grooves(e.g., 12F1) of the spline member and introducer sheath 16A. Thedistances LP1, LP2, and LP3 depend upon the dimensions of the filter 14.In an embodiment suitable for use with the filter illustrated in FIG.7A, 7B, 9A and 9B, the length LP1 is about 6 millimeters and LP2 isabout 34 millimeters so that the total length LP or LP3 is about 40millimeters.

Referring to FIG. 6B, the spline member 12E has a first boss portion12E1 and a second boss portion 12E2 spaced apart from each other todefine a circumferential gap 12E3 therebetween. The gap 12E3 can be anon-annular gap but preferably is an annular gap in the general shape ofa toroid about the longitudinal axis A-A. The first boss 12E1 has aplurality of grooves 12F1-12F6 that extend longitudinally along thelongitudinal axis and are disposed, preferably, arcuately about thelongitudinal axis through the first boss 12E1. In a preferredembodiment, the longitudinal grooves 12F2 define splines 12SP where eachspline extends with a length L of about 3.3 millimeters (about 0.13inches) along the longitudinal axis at a depth DS of about 0.4millimeters (about 0.015 inches) radially with respect to the outersurface of the splines 12SP, having a width of about 0.015 inches.Viewed another way, the first boss features a plurality of longitudinalprojections (i.e., splines 12SP) spaced apart radially from each otherand disposed about a generally cylindrical main surface to define aplurality of longitudinal grooves 12F1-12F6. One longitudinal groove 12Fis provided for each anchor member 14B of the blood filter 14. In theassembled and pre-deployment configuration, the anchor members 14B arefolded down so that a lower portion lies within a groove 12F asillustrated for one anchor member 14B positioned in groove 12F3 in FIG.6C. So configured, the grooves 12F hold the anchor members 14B in place,providing lateral stability necessary to prevent anchor members fromcrossing and becoming entangled during storage and delivery. Similarly,the gap 12E3 provides room for the hook ends of the anchor members to bepositioned so as to prevent interference or entanglement, as illustratedin FIG. 7B.

The second boss 12E2 of the spline member 12E can be a generallycylindrical member disposed about the generally cylindrical mainsurface. As shown in FIG. 6B, a first embodiment of the spline member12E is provided with a non-circular stop member or second boss portion12E2. Alternatively, another embodiment of the spline member 12E isprovided with a generally circular stop member or boss portion 12E2. Inan embodiment, the generally cylindrical boss member includes agenerally planar surface PS disposed about the generally cylindricalsurface CS and spaced apart from a nearest portion of the first boss12E1 at a distance G of about 1.3 mm, or about 0.05 inches, along thelongitudinal axis. The spline member 12E can be made of a suitablematerial including, for example, polymers, metal alloys such as Nitinol,titanium, or stainless steel. Preferably, the spline member 12E is madeof type-303 stainless steel and processed with appropriate deburring andcleaning operations to render the piece suitable for surgical use.

Although the latter embodiment of the spline member 12E in FIG. 6C ispreferred, the former embodiment in FIG. 6B having a non-circular stopmember or boss portion is believed to allow for the control of thespring force during deployment of the blood filter 14 in someapplications of the delivery system 100. Additionally, the non-circularcross section of the second boss 12E2 shown in FIG. 6B permits fluids topass between the spline member 12E and the walls of the introducersheath 16A so saline flow can pass through the filter and so the splinemember 12E does not function as a piston during insertion and withdrawalmovements.

Referring to FIGS. 9A and 9B, two exemplary embodiments of the bloodfilter 14 are shown. Each filter 14 has some common features, Forexample, locator members 14C1, 14C2, 14C3, 14C4, 14C5, 14C6 and anchormembers 14B1, 14B2, 14B3, 14B4, 14B5, and 14B6 are provided that extendin the same direction from a hub 14D1 or 14D2. Hooks 14A1, 14A2, 14A3,14A4, 14A5, and 14A6, each having a smaller cross-sectional area thanthe cross-sectional area of each of the anchor members 14B1-14B6 arerespectively connected to the anchor members 14B1-14B6. The spread ofthe anchor members 14B1-14B6, as measured through the longitudinal axisA-A of the filter 14 or the hub 14D1 or 14D2 is about 40 millimeters ina deployed (but not installed in the blood vessel) position. Differencesinclude the overall length of the two embodiments in which theembodiment of FIG. 9A is about 2 millimeters longer than the embodimentof FIG. 9B in a stored configuration in the storage tube 15; thisdifference in length being due to the snareable hook on the filter 14 inFIG. 9A. The example blood filters 14 also include a hub 14D1, 14D2which can serve as the attachment structure for the anchor and locatormembers. A radio-opaque material can be incorporated in the hub 14D1,14D2 of the filter. Radio-opaque material can be in the form of anadditional structure added to the hub, such as a cap, sleeve, shim, wireor braze included around or in the hub assembly. Alternatively, the hubitself can be fowled of a radio-opaque alloy.

Referring to FIGS. 9C and 9D, details of the snareable tip 14E1 for thehub 14D1 are provided. Specifically, the snareable tip 14E1 is believedto allow, optionally, for repositioning (e.g., by capturing and pullingthe filter into a catheter) or potentially complete removal of thefilter. The snareable tip is provided with a protuberance 14E3 to ensurethat a snare will tend to be retained proximate the radiused surface R1.To assist in the capture of a snare (not shown), second radiused surfaceR2 is included to provide a generally smooth guided entry into the firstradiused surface R1. Assisting second radiused surface R2 are taperedside surfaces 14E5 having an included angle α of about 160 degrees. Thethickness TL of the tip 14E1 is preferably about 0.5 millimeters (about0.02 inches), the overall length of the tip and hub is preferably about7.6 millimeters (about 0.3 inches), and the hub 14D1 is preferablygenerally circular with an outer diameter of about 1.8 millimeters(about 0.07 inches).

Additional details of the blood filter 14 are provided in provisionalpatent application Ser. No. 60/680,601 filed on May 12, 2005, which isincorporated by reference in its entirety herein, and as well as in aPCT Patent Application that claims priority to the antecedentprovisional patent application, which PCT Patent Application is entitled“Removable Embolus Blood Clot Filter,” with Attorney Docket No.14673-002W0 and PCT Application No. PCT/US06/17889 filed on May 9, 2006,and both applications are hereby incorporated by reference in theirentirety.

An alternative embodiment for the splined member 20 is illustrated inFIGS. 10 and 11. Referring to FIG. 10, in this embodiment of the splinedmember 20, the spline portions 20C are provided within the boss 20B. Inthe embodiment illustrated in FIG. 10, the boss 20B features a first,distal conical surface 20D and a second, proximal conical surface 20Eprovided before a shaft portion 20A and an end, connector portion 20F.The end portion 20F can include a central bore that may be threaded toaccept the distal end of the elongated pusher member 12B4. Grooves 20Cprovided in the boss 20B are configured to accommodate and radiallyposition the anchor members 14B. In an embodiment illustrated in FIGS.10 and 11, the grooves 20C are narrower at a distal end 20C 1 than atthe proximal end 20C2.

Referring to FIG. 11, the conical configuration of portions 20D and 20Eare provided so that when the anchor 14 is positioned within the spline20C, the hook 14A portion fits over the proximal conical portion 20E sothat the diameter subtended by the hooks 14A positioned about the boss20D is less than the interior diameter of the introducer 16. In anembodiment, where the anchors 14 have a narrower width (or crosssection) in the hook portion 14A than the shank portion 14B, thenarrower distal portion 20C1 of the splines 20D has a groove 20C whosewidth (as measured on an imaginary outermost circumference connectingthe splines 20D) or cross section is smaller than the width or crosssection of the anchor shank 14B. In this embodiment, the anchor 14features a conical shaped portion 14AB where the cross section decreasesfrom that of the shank portion 14B to the hook portion 14A. In otherwords, at least one anchor portion (e.g., 14B1, 14B2, 14B3, 14B6) of afilter 14 can be located in at least one of the plurality of grooves 20Ddisposed between splines 20D where the anchor portion (having portions14A and 14B) has a maximum width at portion 14B greater than a minimumwidth 20C1 of the groove. Since the narrow portion 20C1 of the spline20C is wider than the cross section of the hook portion 14A but narrowerthan the anchor shank portion 14B, the narrow portion 20C1 will engage(e.g., in an interference fit) a portion of the anchor transitionportion 14AB. When the anchors 14 are positioned within the grooves 20Cin this embodiment, the anchor 14 cannot move in a proximal directionbeyond the point where the anchor transition portion 14AB engage thenarrow portion 20C1. In this manner, the spline 20C restrains the anchor14 longitudinally. It should be noted that the narrower portion 20C1does not have to be located at the proximal end of the boss 20B.Depending on the length of the hook portion 14A, the narrower portion20C1 can be disposed at any one of a plurality of positions between 21A,21B, and 21C.

Several design features are believed to be important in advancing thestate of the art. For example, the use of the splined member 12E isbelieved to be important in preventing a pull back of the blood filter14 from the storage tube 15 toward the proximal direction. Specifically,the spline member 12E is provided with a gap 12E3 to store the hooks ofthe blood filter 14 in a pre-delivery configuration (FIGS. 6C, 7A, and7B) that forms an interference fit between the hooks 14AC, the splinemember 12E and the storage tube 15 and introducer sheath 16A. Forclarity, only one anchor member 14B and Hook 14A are shown in FIG. 6C.However, the anchor members 14B1, 14B2, 14B3, 14B4, 14B5, and 14B6 onwhich the hooks 14A are respectively connected are in a spiralconfiguration as shown in the side view of FIG. 7A while the hooks areshown in the sectioned-view of FIG. 7B. The placement of the hooks, asshown in the example of FIGS. 6C and 7A, presses the anchor membersagainst the wall of the storage tube 15 and introducer sheath 16A, withthe of the hook tip 14B angled in a proximal direction and in contactwith the wall as illustrated in FIG. 7B elements 14B1, 14B2, 14B3, 14B4,14B5, and 14B6. When the filter 14 is advanced in the distal direction,the hook tips 14B slid easily along the wall of the storage tube 15 andintroducer sheath 16A. However, if the filter 14 is moved in theproximal direction (towards the right side of FIG. 6C), the taperedsurface 12E4 (FIG. 6C) causes a portion of the hook 14A to slide up onthe tapered surface 12E4. Because at least the hook 14A is constrainedbetween the spline member and the introducer sheath 16A, a portion ofthe hook 14A engages one of the wall of the storage tube 15 andintroducer sheath 16A in a ratchet-like fashion, presenting a highresistance to motion in that distal direction. As a consequence of thisconfiguration of the filter about the splined member 12E, approximately5 pound-force is required to cause the filter 14 and pusher assembly 12to move toward the user or operator (i.e., in a proximal direction) butgenerally little or no force for movement away from the user or operator(i.e., in a distal direction). That is, the placement of the hooks 14Ain relation to the spline member 12E and the storage tube 15/introducersheath 16A prevents proximal movements of the elongated assembly 12 ifthe force applied to the assembly 12 is less than a desired value. Itshould be noted that the desired force value can be selected as beingmore or less than approximately 5 pound force as a function of at leastthe cross-sectional area of the hooks 14, the configuration of thespline member 12E (e.g., the angle of tapered surface 12E4), and theinside diameter of the storage tube 15 and introducer sheath 16A. Thisdesign feature is believed to prevent inadvertent dislodgement of theanchors from the spline member, which may cause crossing of the anchors.

Additionally, the use of the splined member in the various embodimentsdescribed herein is believed to alleviate the problem of the pluralityof hooks crossing each other as they are mounted in the storage tube 15or while the filter is being deployed via the introducer sheath 16A(regardless of whether the filter and system are being tested inside oroutside of a host body). In particular, the longitudinal grooves12F1-12F6 (which can be linear, curved or curvilinear) positionedcircumferentially about the longitudinal axis A-A, in combination withthe gap 12E3 allows the anchor members 14B and associated hooks 14A tobe held in a generally precise configuration (FIG. 7B) while in storageand during delivery into a vein to virtually eliminate the entanglementor crossing of the hooks.

In particular, the use of the splined member 20, shown and described inrelation to FIGS. 10 and 11, is believed to reduce a force needed by aclinician to deploy the filter 14 from the distal tip of the introducerduring an implantation procedure. The use of spline member 20 reduces aninteraction between hooks, sheath wall and marker band to reducedeployment force. Testing has demonstrated the axial force applied tothe pusher is approximately 2 lb-force when the spline member 20 (FIG.10) is utilized.

Further, the use of the complementary snap-fittings for the storage tube15 and introducer body 16C along with the internal and external tapers16F and 15C is believed to allow for precise coupling of the twocomponents without having to align the storage tube with the body 16Cand threading the two components together, which under somecircumstances could result in cross-threading or interference with thetip of the filter 14 into the introducer sheath 16A.

By virtue of the delivery system 100, among other items, described andillustrated herein, a method of packaging a blood filter 14 is provided.As noted above, the filter 14 includes a plurality of anchor members14B1-14B6 about a longitudinal axis; each of the anchor members14B1-14B6 having a hook 14A and at least two of the anchor members14B1-14B6 defining a span intersecting the longitudinal axis and betweenthe at least two anchor members of about 40 millimeters. The method ofpackaging the filter 14 including hooks 14A having a cross sectionalarea Al along the arcuate portion 14AC of the hook 14A that is greaterthan about 0.04 squared millimeters (or about 0.000057 squared inches),involves locating the curved portion 14AC of each hook in the annulargap 12E3 disposed between the first and second boss portions 12E1 and12E2 of spline member 12E; and enclosing the filter 14, including theplurality of locators and hooks, and the boss portions in a generallytubular storage tube (e.g., storage tube 15 or introducer sheath 16A)having an outside diameter of less than about 10 French (about 3.3millimeters) and preferably about 9 French (about 2.9 millimeters) andan inside diameter less than 9 French, preferably less than about 7French (about 2.3 millimeters). By virtue of the configuration of theblood filter 14 with its hooks 14A, spline member 12E and storage tube15, the enclosing step further includes preventing movement of thefilter 14 relative to the generally tubular member 15 along thelongitudinal axis upon application of axial force of less than 5Pound-force in a proximal direction.

This assembly process for mounting the blood filter on the spline member12E and loading it into the storage tube 15 is performed prior toshipment to the user or medical practicitioner. In an embodiment, thehub 14D of the filter 14 is positioned on the distal end of the pushermember 12C of the pusher assembly 12. The hub is then inserted into theproximal end of the storage tube 15, and as it is advanced thepositioning members 14C displaced radially inward to allow the filter 14to advance into the storage tube 15. Then the anchor members 14A aredisplaced radially inward as the filter 14 is further advanced into thestorage tube 15. As the filter 14 is advanced, the anchor members 14Aare positioned one to a groove in the spline portion 12E1 of the splinemember 12E, with the hooks 14A1-14A6 fitting into the gap 12E3 in aspiral fashion as illustrated in FIG. 7B. Finally, the filter 14 andpusher assembly 12 are advanced into the storage tube 15 so that theentire spline member 12E is encompassed within the storage tube 15 asillustrated in FIG. 6C. The assembly may further be facilitated by usinga jig or other assembly tool to guide the filter members into properposition for loading into the storage tube 15.

To complete assembly, the storage tube 15 can be sealed on both ends toprevent contamination from entering, and the entire assembly of thepusher assembly 12, filter 14 and storage tube 15 sealed in sterilepackaging. To avoid kinking of the pusher assembly 12 or lateral forceson the storage tube 15, the entire assembly can be packed in a linearmanner within a foam form and hard outer package, such as cardboard orplastic. In a preferred embodiment, the entire assembly is packaged astwo separate sterilized units with the introducer and dilator as onesterilized unit and the filter/pusher assembly in a separate sterilizedunit.

In an alternative embodiment of the pusher assembly, 12, the distal endfrom the spline member 12E through the pusher member 12C is configuredas one piece, and the proximal portions of the pusher assembly, fromhandle 12A through wire 12B4, configured is one or more pieces, with acoupling mechanism provided for connecting the spline member 12E to thedistal end of the push wire 12B4. This embodiment is illustrated inFIGS. 6D, 6E and 6F. As illustrated in these figures, a variety ofconnection couplings can be used to connect the pusher wire 12B4 to thespline member 12E. By way of example, connector embodiments may includea bayonet connector as illustrated in FIG. 6D, which features a bayonetcoupler 16H including tangs 16H1 connected to the push wire 12B4 whichengages a bayonet coupling 12H2 within the spline member 12E. Anotherexample; a threaded connection 12G as illustrated in FIG. 6E, which mayincluded a threaded tip 12G1 on the end of the push wire 12B4 whichthreads into a complementary threaded hole 12G2 in the spline member12E. A further example is a spring and latch assembly 12J illustrated inFIG. 6F, that can include spring latches 12J1 mounted on the distal endof the push wire 12B4 which expand into a latching recess 12J2 withinthe 12E when the distal end of the push wire 12B4 is pushed into thelatch opening 12J3. These embodiments permit the filter-splinemember/pusher member assembly to placed inside the storage tube 15, suchas per the procedure described above, and sealed and stored (such aswith caps on each end of the storage tube 15) separate from the longpusher assembly 12A-12B4. Disconnected from the push wire, thefilter-spline member-pusher member assembly is less likely to besubjected to lateral forces during shipping, storage and handling.Further, damage to either the push wire 12 or the storage tube 15 doesnot require the other component to be disposed of. Further, the pushwire 12 can be stored in a coiled fashion and uncoiled before assemblingto the filter.

In operation for implanting a blood filter into a host, a suitablefemoral venous vessel site in the host may be selected. Typically, thisis the femoral vein on either the left or right side, depending upon thepatient's size or anatomy, the clinician's preference and/or thelocation of a venous thrombosis. The site can be nicked with a blade andthe vein punctured with a suitable entry needle, such as an 18 gageneedle, or trocar. A Suitable guidewire, such as a J-tipped guidewire,is inserted into the needle and advanced into a distal vena cava oriliac vessel where a filter is to be delivered. Once the guidewire is inposition, the entry needle is removed from the patient and slipped offthe proximal end of the guide wire. Then the proximal end of theguidewire is inserted into the introducer distal tip 16A1. Saline or asuitable bio-compatible fluid is provided to the introducer valve 16D toremove air in the introducer 16, and then introducer tip 16A1 isinserted into the patient and advanced along the guidewire until itreaches the desired position in the vena cava or iliac vessel.Positioning of the introducer tip 16A1 within the vein at the site fordelivering the filter may be confirmed by fluoroscopy, aided by theradio-opaque markers on or within the introducer 16. The dilator tube18B is then inserted through the introducer body 16C until the dilatorhub 18A is snap-fitted onto the coupling port 16B of the introducer 16.Contrasting agent or dye can also be provided to the ports 18D of thedilator tube 18B via the dilator body 18A to provide for visual imagingof the introducer tip 16A1 via suitable fluoroscopic imaging equipment.The guidewire and the dilator 18 can be removed once the user orphysician has determined that the introducer tip 16A1 is at the desiredlocation in the vein or vessel.

Saline infusion can be supplied to the Touhy-Borst Adapter 10. Thefilter 14, which is pre-stored in the storage tube 15, can be coupled tothe coupling port 16B via the snap-fitting, and saline can be permittedto flow through the storage tube 15 to provide lubricity between variouscomponents of the delivery system 100. The saline may be chilled duringportions of the procedure. Similarly, the saline may be warmed duringportions of the procedure, such as just prior to releasing the filterinto the vein, to help raise the filter and pusher assembly 12components above the martensitic-to-austenitic transition temperature,causing the filter to seek its annealed shape. The introducer 16,storage tube 15 and elongated pusher assembly 12 are preferably held ina linear configuration to avoid kinking and minimize friction. Thefilter 14 is physically advanced from the storage tube 15 through theintroducer 16 to a position near the distal tip 16A1 of the introducer16. The advancement of the filter 14 can be accomplished by maintainingthe introducer 16 stationary while pushing on the handle 12A of theelongated pusher assembly 12 in the distal direction. The filter 14 ismaintained inside the introducer 16, i.e., undeployed at this point.Markings on the pusher assembly 12 may permit the clinician to know theposition of the filter 14 with respect to the end of the introducer 16.Additionally, fluoroscopy may be used to track the position of thefilter 14 within the introducer 16 and with respect to the patient. Whenthe filter hub 14D approaches the distal end of the introducer 16, thefilter is ready-to be deployed.

To deploy the filter 14, the elongated pusher assembly 12 is heldstationary while the introducer sheath 16A is pulled back in theproximal direction. This causes the filter to remain in position withinthe vein, held in place by the pusher member 12C, while the introducersheath 16A pulls back to release the locator members 14C. Since thelocator members 14C are shorter than the anchoring members 14B, thelocator members are released first, allowing them to spring out untilthey contact the walls of the vein. This action places lateral forces onthe vein which causes immediate centering of the filter 14 within thevein. A simulation of the deployment of the filter 14 is shown in FIG.8.

As the introducer 16 is further retracted proximally, the anchor members14B1-14B6 become unconstrained by the introducer sheath 16A and are freeto expand radially. Due to the preload in the push wire portion 12B6which applies a force through the pusher pad 12C upon the hub of thefilter, the filter is released out of the introducer sheath as soon asthe hook portions 14A are released from the spline member 12E. Hooks 14Aat the ends of the anchor members' 14B1-14B6 begin to dig or penetrateinto the blood vessel wall to maintain the filter 14 at approximatelythe desired location.

Additional information on deployment of this type of filter referencedin the Information for Use is shown and described in U.S. patentapplication Ser. No. 09/640,865, filed on Aug. 18, 2000, pending, U.S.Pat. Nos. 6,258,026; and 6,007,558. Each of the previously mentionedapplication and patents is incorporated by reference herein in itsentirety into this application.

In another embodiment, bio-active agents can be incorporated with theblood filter or filter delivery system, such as by way of a coating onparts of the filter delivery components (e.g., the pusher pad 12C or thetip of the introducer sheath 16A), or dissolvable structures on, withinor attached to the filter delivery components. Alternatively, bio-activeagents can be delivered to the region of the filter at the time of thefilter emplacement by means of the introducer, either before or afterdelivery of the filter. Bio-active agent can be included as part of thefilter delivery system in order to treat or prevent other conditions(such as infection or inflammation) associated with the filter, or totreat other conditions unrelated to the filter itself. Morespecifically, bio-active agents may include, but are not limited to:pharmaceutical agents, such as, for example,anti-proliferative/antimitotic agents including natural products such asvinca alkaloids (i.e. vinblastine, vincristine, and vinorelbine),paclitaxel, epidipodophyllotoxins (i.e. etoposide, teniposide),antibiotics (dactinomycin (actinomycin D) daunorubicin, doxorubicin andidarubicin), anthracyclines, mitoxantrone, bleomycins, plicamycin(mithramycin) and mitomycin, enzymes (L-asparaginase which systemicallymetabolizes L-asparagine and deprives cells which do not have thecapacity to synthesize their own asparagine); antiplatelet agents suchas G(GP) IIb/IIIa inhibitors and vitronectin receptor antagonists;anti-proliferative/antimitotic alkylating agents such as nitrogenmustards (mechlorethamine, cyclophosphamide and analogs, melphalan,chlorambucil), ethylenimines and methylmelamines (hexamethylmelamine andthiotepa), alkyl sulfonates-busulfan, nirtosoureas (carmustine (BCNU)and analogs, streptozocin), and trazenes-dacarbazinine (DTIC);anti-proliferative/antimitotic antimetabolites such as folic acidanalogs (methotrexate), pyrimidine analogs (fluorouracil, floxuridine,and cytarabine), purine analogs and related inhibitors (mercaptopurine,thioguanine, pentostatin and 2-chlorodeoxyadenosine {cladribine});platinum coordination complexes (cisplatin, carboplatin), procarbazine,hydroxyurea, mitotane, aminoglutethimide; hormones (i.e. estrogen);anti-coagulants (heparin, synthetic heparin salts and other inhibitorsof thrombin); fibrinolytic agents (such as tissue plasminogen activator,streptokinase and urokinase), aspirin, dipyridamole, ticlopidine,clopidogrel, abciximab; antimigratory agents; antisecretory agents(e.g., breveldin); anti-inflammatory agents, such as adrenocorticalsteroids (cortisol, cortisone, fludrocortisones, prednisone,prednisolone, 6a-methylprednisolone, triamcinolone, betamethasone, anddexamethasone), non-steroidal agents (salicylic acid derivatives i.e.aspirin; para-aminophenol derivatives i.e. acetaminophen; indole andindene acetic acids (indomethacin, sulindac, and etodalac), heteroarylacetic acids (tolmetin, diclofenac, and ketorolac), arylpropionic acids(ibuprofen and derivatives), anthranilic acids (mefenamic acid, andmeclofenamic acid), enolic acids (piroxicam, tenoxicam, phenylbutazone,and oxyphenthatrazone), nabumetone, gold compounds (auranofin,aurothioglucose, gold sodium thiomalate); immunosuppressives:(cyclosporine, tacrolimus (FK-506), sirolimus (rapamycin), azathioprine,mycophenolate mofetil); angiogenic agents, such as vascular endothelialgrowth factor (VEGF), fibroblast growth factor (FGF); angiotensinreceptor blockers; nitric oxide donors; anti-sense oligionucleotides andcombinations thereof; cell cycle inhibitors, such as mTOR inhibitors,and growth factor receptor signal transduction kinase inhibitors;retenoids; cyclin/CDK inhibitors; HMG co-enzyme reductase inhibitors(statins); and protease inhibitors.

While the present invention has been disclosed with reference to certainpreferred embodiments, numerous modifications, alterations, and changesto the described embodiments are possible without departing from thesphere and scope of the present invention, which is described, by way ofexample, in the appended numbered paragraphs below. Accordingly, it isintended that the present invention not be limited to the describedembodiments, but that it have the full scope defined by the language ofat least the following paragraphs, and equivalents thereof.

What is claimed is:
 1. A filter system comprising: a filter having aplurality of hook-terminated anchor members wherein at least one anchormember comprises a tapered anchor portion with a maximum width adjacentto the hook; and a pusher assembly including a spline having taperedgrooves each groove engaging a section of the tapered portion.
 2. Thesystem of claim 1 wherein the spline has a boss and the boss comprisesprojections disposed about a main surface to define the tapered grooves.3. The system of claim 2 wherein the filter is a blood filter.
 4. Thesystem of claim 3 wherein the blood filter is a vena cava filter.
 5. Thesystem of claim 4 wherein a groove engages a tapered portion in aninterference fit.
 6. The system of claim 5 further comprising one ormore additional bosses.
 7. The system of claim 6 wherein a projection islongitudinally disposed.
 8. The system of claim 7 wherein an anchormember is longitudinally disposed.
 9. The system of claim 6 wherein ananchor member is longitudinally disposed.
 10. The system of claim 9further comprising one or more additional bosses.
 11. The system ofclaim 5 wherein a groove engages a tapered portion in an interferencefit.
 12. The system of claim 1 wherein a projection is longitudinallydisposed.
 13. The System of claim 12 wherein an anchor member islongitudinally disposed.
 14. The system of claim 13 wherein an end of ahook is positioned outside of a groove.
 15. The system of claim 14wherein the pusher assembly includes an elongated member, and whereinthe spline member is disposed along a distal section of the elongatedmember.
 16. The system of claim 6 wherein the pusher assembly includes ahandle at a proximal end of the elongated member and a pusher pad at adistal end of the elongated member, and wherein the spline member isdisposed between the handle and the pusher pad.
 17. The system of claim1 wherein the anchor portion has a frustoconical shape, has a firstdiameter equal to the maximum width, and has a second diameter smallerthan the first diameter and wherein the section of the tapered portionincludes the second diameter.
 18. The system of claim 17 furthercomprising one or more additional bosses.
 19. A filter systemcomprising: a vena cava filter having a plurality of hook-terminated,longitudinally disposed anchor members wherein an anchor membercomprises a tapered anchor portion with a maximum width adjacent to thehook and with a first diameter equal to the maximum width and a seconddiameter smaller than the first diameter; and a pusher assemblyincluding: an elongated member having a handle at a proximal end, apusher pad at a distal end; and a distal section between the handle andthe pusher pad; and a spline member disposed along a distal section ofthe elongated member wherein the spline member has: tapered grooves eachgroove engaging at least the second diameter of the tapered portion inan interference fit; and a plurality of bosses at least one bosscomprising a plurality of projections longitudinally disposed about amain surface to define the tapered grooves, wherein an end of each hookis positioned outside of the plurality of grooves.